1. Technical Field
The present disclosure relates to fluid control valves and, more particularly, to fluid control valve arrangements for water treatment equipment, such as ion exchange water softeners and media filters.
2. Description of the Related Art
Fluid control valves are generally used for water treatment systems, such as water softeners that remove certain minerals from the water as delivered to the end user. Such minerals (e.g., calcium, magnesium, manganese and iron) contribute to what is commonly referred to as water “hardness.” Water softener systems may employ an ion exchange process to bond the minerals to other materials. Such ion exchange may be effected by providing an ion exchange resin bed containing resin materials designed to promote the ion exchange process. The resin bed is housed in a resin tank which is filled with some of the water from the water source. As this water passes across the resin bed, ions of calcium and other positively charged ions are exchanged with ions held by the resin (typically sodium). Objectionable hardness minerals are thereby removed from the water and replaced with less objectionable ions from the resin.
Ion exchange resin capacity is gradually depleted as the ion exchange process is repeated over time. Water treatment controls may be provided as part of a water softener system to periodically regenerate the resin contained in the resin tank. This regeneration can be accomplished, for example, by the reversal of the above-described softening process. That is, the objectionable ions formerly bonded to the resin during the water softening process (such as calcium) are chemically replaced with less objectionable sodium or similar ions. In some systems, this reversal is accomplished by passing a regenerant solution of sodium or potassium chloride through the resin bed.
To effect distribution of the regenerant solution, a control valve may be attached to the top of the resin tank. The control valve includes a structure for directing the flow of fluid to complete the regeneration process, such as a reciprocating piston, rotating disc or poppets. The regeneration process controlled by the control valve may include a number of steps, such as: i) a backwash cycle to remove turbidity from the resin bed; ii) a brine draw cycle to introduce the regenerant to the resin bed; iii) a rinse to eliminate chlorides in the finished water; and iv) a brine refill cycle to prepare a brine solution for the next regeneration. During the time elapse during these various cycles, the control valve may also provide an internal bypass to provide untreated water to the end user, so that water supply remains uninterrupted.
In addition to the application of a water softener as described above, a fluid control valve can be used on various water filters. Control valves used on water filter systems may, for example, be used to effect a backwash cycle to remove collected precipitated iron, or sediment from filter elements, or to replenish an oxidizer reservoir within the filter system with material for oxidation (e.g., potassium permanganate, chlorine or air).
Reciprocating piston type water treatment control valves generally have a seal arrangement contained within a cylindrical bore and surrounding a piston. In these types of arrangements, a motor may drive the piston axially to selectively connect particular inlet and outlet ports, thereby cycling the valve through various positions involved in the regeneration process. The piston moves to connect ports in various combinations, as the respective seals provide a water tight barrier between ports. The seal arrangement may be separate individual seals arranged next to one another, or they may be joined together.
Seal arrangements usable with a water treatment control valve may be pre-compressed stacks. In some cases, this type of pre-compressed seal stack has the various individual seals and associated spacers therebetween welded or screwed together.
U.S. Pat. No. 6,402,944 (“the '944 patent”) describes a seal assembly that can be preassembled prior to insertion in the valve bore. Unlike the seal designs including pre-compressed stacks of seal components, the seals of the '944 patent includes various seals that are not compressed until the assembly is fully inserted.
The resin bed of water treatment systems is often made up of a reservoir of salt. In order to prevent depletion of the salt reserves, some devices indirectly monitor the salt level in the salt storage reservoir by using an electronic controller to calculates how much salt from the reservoir has been used based on the number of regenerations that have occurred and the amount of salt programmed to be used per regeneration. When the controller determines that the reservoir's salt reserves should be depleted, an operator may be alerted to refill the reservoir and then manually reset the salt-level monitor to once again begin counting the number of regeneration cycles completed. Such manual resetting may be accomplished, for example, by pushing a reset button when salt is added or placing a float on top of the salt each time the salt is replenished.
Another previous idea is a paddle located in the salt tank that is pushed when in contact with salt. If salt level drops below the paddle a circuit is completed and a user is notified of the low level. In some cases, however, salt may engage the paddle at such an angle as to jam the paddle and prevent actuation.
Yet another monitoring methodology measures the conductivity of the brine solution and indicates the need for salt replenishment when the conductivity drops by a certain amount. In these systems, the monitor must be submerged in the corrosive brine solution. Indication of a low salt level (and therefore, of the need to replenish the salt reserves) will occur only after substantially all of the salt is consumed.